High-density brine fluids are known to be applied in situations where control of pressure in a well is needed. Many different soluble salts may be used to achieve the desired density of the aqueous solution. The more common salts used include, but are not necessarily limited to, chloride and/or bromide salts of the following cations: sodium, potassium, calcium and zinc. These salts impart density to the aqueous fluid by dissolving in the medium. A high-density fluid may be understood as one of greater than about 8.4 pounds/gallon (1.0 kg/l) density, preferably from about 8.4 to about 22.5 lbs/gal. (1.0-2.7 kg/l), most preferably from about 9.0 to about 22.0 lbs/gal. (1.1-2.6 kg/l).
The density of these solutions made by dissolving these salts in water is limited by the molecular weight and the solubility of that salt. Zinc is a preferred cation. Zinc salts are desired as components of high-density brines because of their relatively high molecular weight and great solubility in water.
Brines, including zinc-containing brines, have low pH in aqueous solutions inherently. The acid content of these fluids give the brines undesirable characteristics, one of the greatest of which are high corrosion losses that limit the uses and applications of these fluids.
A method and composition that would overcome some of the problems in the conventional brines, particularly high-density brines, would be desirable.